SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1d98681e03455d51bc0f2f7b0711fca256466e096fac736b1a3723b44acbfdc4' 
  AND token = 'Tmi+oFhf+fPI6Ih7Kjvwj5jy9wtvYMV3RKvsyGDvL/c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}